To increase capacity of magnetic storage systems, efforts are continually made to increase magnetic recording density. Three competing requirements affect how densely data can be written to a magnetic recording medium: writeability, readability, and stability. Writeability refers to how densely data may be written to the magnetic recording medium. Readability refers to whether a magnetic reader can accurately read data written to the magnetic recording medium at a particular densely, and stability means whether the data—once written—retains the desired direction of magnetization (i.e., does not “flip” directions). For example, as bit size of data written to the magnetic media decreases in size, the coercivity of the material must increase in order to maintain the desired stability. As the coercivity of the material increases, the magnitude of the magnetic write field required to change the magnetic orientation of a particular bit becomes prohibitively large. That is, the coercivity is so high that the magnetic field cannot be made strong enough to permanently affect the direction of magnetization and data can no longer be written to the disk.
Heat-assisted magnetic recording (HAMR) provides one method of overcoming this limitation to traditional magnetic recording. In a HAMR system, a laser or other heat source is used to supply a high-temperature thermal pulse to the area of the magnetic media being written. By heating the magnetic media, the coercivity of the material is temporarily lowered, allowing a corresponding magnetic write field to change the magnetic orientation of the bit to a desired direction. Once the bit has been written, the magnetic media cools and the coercivity increases to a level that provides the desired stability.
One drawback of HAMR is that the high-temperature thermal pulse applied to the magnetic media causes carbon oxidation of the magnetic media. That is, some of the material itself is eroded with each write operation. After a certain number of write operations, the material is sufficiently eroded that it can no longer be written to.
It would therefore be beneficial to reduce the effect of these high-temperature thermal pulses on the magnetic media.